pistons

[JohnsonM50]

Im building several OMC 31.8s- 25/35 hp- deflecter pistons. Ive used stock & Wiseco pistons before, the Wisecos seem to be lighter but run about the same. What are [if any] other choices ? Any opinions on the best performance brand? Thanks, Mike.

[JohnsonM50]

Im building several OMC 31.8s- 25/35 hp- deflecter pistons. Ive used stock & Wiseco pistons before, the Wisecos seem to be lighter but run about the same. What are [if any] other choices ? Any opinions on the best performance brand? Thanks, Mike.

120 looks & no answers, Oh well. I did find out something of interest for anyone boring a 31.8 out, mines 0.030 oversize. It broke & ingested a reed petal so it had to come apart. Its been run about 25 hrs, mostly WOT.
The cyl sleeves stop about 9/16" short of the bottom of the exhaust side of the casting. [they reach the bottom of the intake side]. From being bored the steel of the sleeve was cut to be flush with the aluminum of the block. This is scratched up as well as about the bottom 1/2" of that side of the piston. Ill have to get in there & clearance that a bit I guess. Something I shouldve seen & addressed then but at least I get a 2nd chance now.

[Skoontz]

There is a new brand that just got approved by APBA for OMC A motors, not sure of brand, but, the general consensus was that they were better, and, they were cast not forged like Wisco.

Sorry not to be of any more help....

[JohnsonM50]

There is a new brand that just got approved by APBA for OMC A motors, not sure of brand, but, the general consensus was that they were better, and, they were cast not forged like Wisco.

Sorry not to be of any more help.... Thanks Bill, maybe somethin'll turn up. I thought I read of a 3rd kind as well as some of these motors being built to race... is it secret? :D

[Boatwrx]

The Pistons (class A OMC) in question are made by GLM. Part number 24430 (for .030 over). This kit includes the piston, rings, wrist pin and keepers. Replacement rings are part number 23730 (2 per set). I sell the piston kits to racers for $45.00 (list $58.00) and the ring sets for $19.00 (list 31.00). They make a full range of cast pistons for OMC and Mercury outboards. Freight is normally just a few dollars.

Hope this helps,

Ken Scoville
www.boatwrx.com
Boulder, CO

303-440-0854

[Bill Gohr]

We actually made high ringers for those if you can find them

[Ron Hill]

I noticed that Wiseco's 45 piston had a lower ring.....than the OEM ring. Now, you are telling me that some 25-35 have high rings???

That is bad new for a stock class, I feel...Which motors came with high rings? Were there ever .030 high rings.


Seems to me this GT PRO class rules should address the high ring, as I see this as a PROBLEM BREWING...

How much would you need to take off a head to make up for a high ring piston?

[Skoontz]

Ron:

Heres something that is pretty weird, beleive it or not. I'm going from the fastest A stock motors here, but, the ones really cooking have low to mid compression, and actually 1cc more room in the chambers than others running good. Clearance of .0055 from piston skirt to piston seem to be whats working.

If you take this model to Mini GT, (we are talking stock motrs right?) you should check to see if a hig ringer is in fact producing more than the other ring and model from that...At least in what my simple cavemen landscaper mind is thinking....

[JohnsonM50]

The Pistons (class A OMC) in question are made by GLM. Part number 24430 (for .030 over). This kit includes the piston, rings, wrist pin and keepers. Replacement rings are part number 23730 (2 per set). I sell the piston kits to racers for $45.00 (list $58.00) and the ring sets for $19.00 (list 31.00). They make a full range of cast pistons for OMC and Mercury outboards. Freight is normally just a few dollars.

Hope this helps,

Ken Scoville
www.boatwrx.com
Boulder, CO

303-440-0854 Thanks Ken, Im workin with late 70s early 80s 25/35 31.8ci OMCs. Theres 2 piston versions I know of, 5/8" wrist pin & later 3/4", lighter, stronger 3cyl rods can be used with the 3/4 pins.

[Bill Gohr]

Yes we made high ring forged pistons for the 32 cuber you'll find them in 81' 82' 83' stuff, the 82' 35hp was the strongest 32 if you're wanting one of those engines. We changed the rods in 77 or 78'. The high ringers were great cheaters in the Mini Grand Prix motors when my Wife ran MGP, not that there were any in her engine.......

[JohnsonM50]

Yes we made high ring forged pistons for the 32 cuber you'll find them in 81' 82' 83' stuff, the 82' 35hp was the strongest 32 if you're wanting one of those engines. We changed the rods in 77 or 78'. The high ringers were great cheaters in the Mini Grand Prix motors when my Wife ran MGP, not that there were any in her engine.......
Bill, I remember your mentioning the 82 being the strongest some time back, Are the hi ring pistons the reason for this? Ive had an ear out for an 82 since but so far no luck. Now Im reaching.. but if the pistons are the secret then would putting them in another year block make the difference?

[JohnsonM50]

I was lookin thru some parts & came across the hi ring type piston, besides the ring being very near the top its got a different type top ring. Turns out also that I put a stock block on my hydro to run while rebuilding, ran it w/o gps & thought this motors quick! [& sounds different].Turns out its a hi ring type too. These are OMC pistons, as far as I know. Im already into one of my 35s with Wisecos but look forward to re-doin one with these. :cool::D

[JohnsonM50]

I was lookin thru some parts & came across the hi ring type piston, besides the ring being very near the top its got a different type top ring. Turns out also that I put a stock block on my hydro to run while rebuilding, ran it w/o gps & thought this motors quick! [& sounds different].Turns out its a hi ring type too. These are OMC pistons, as far as I know. Im already into one of my 35s with Wisecos but look forward to re-doin one with these. :cool::D
Next Q..Were these hi ring pistons made for the 22 ci OMCs? The 22s will give a 32 a run for its inches except where weight is.. on the 32s side.